| Objectives To determine the association between body mass index(BMI)and the duration of mechanical ventilation and hospital mortality for mechanically ventilated intensive care unit(ICU)patients.Methods This is a prospective observational cohort study of consecutive ICU patients who required mechanical ventilation for greater than 48 h in North China University of Science and Technology affiliated hospital between January 1,2015 and December 31,2015 was conducted.The criteria for exclusion were patients:(1)age less than 18 years,(2)with severe fluid retention,e.g.pleural effusion or peritoneal effusion,(3)pregnant woman,(4)patients who transferred from other facilities who had already been intubated and ventilated,(5)with the BMI less than 18.5kg/m2,(6)brain death on arrival to ICU or care withholding,(7)patients with more than one ICU admission during the study period,(8)no surrogate decision maker or declined enrollment,(9)weight measurements could not be used on admission to the ICU or hospital,or the weight data of recent 3 month were not available from patient care providers,(10)with limb amputations.All outcomes were analyzed separately according to BMI: obese(BMI ≥3 0 kg/m2)versus non-obese(BMI 18.5 kg/m2 to <30 kg/m2).The primary outcome measures were hospital mortality and duration of mechanical ventilation.The secondary outcomes included ICU mortality,60-day mortality,the length of ICU and hospital stay,the rate of prolonged mechanical ventilation(> 21 d),the rate of reintubation,the rate of tracheostomy,the rate of ventilator associated pneumonia,the rate of central line-associated blood stream infection,the rate of deep venous thrombosis and the rate of decubitus.The statistical analysis was performed using SPSS version 17 for Windows.Among included patients,basic descriptive characteristics were compared according to obesity status using t tests for continuous variables and χ2 or Fisher’s exact testing for categorical variables.Multivariable forms of logistic was also undertaken in an attempt to isolate the relationship of obesity and the hospital mortality apart from associated potential confounders.Results Two hundred and ten patients were enrolled in the study: 84 in obese group and 126 in non-obese group.No patient was lost of follow up and withdrawed during the study.The BMI of obese group was 31.00±3.60 kg/m2,and the BMI of non-obese group was 21.66±1.43 kg/m2(P< 0.001).Moreover,there were no difference in the way of age,sex,the score of APACHE II,the source of patients,underlying disorders,the smoking habit,and the oxygenation index.Obesity was associated with a longer duration of mechanical ventilation(15.0 vs.12.1 d,P=0.011),length of ICU and hospital stay(22.0 vs.16.0 d,P = 0.040;31.5 vs.27.5 d,P = 0.017,respectively),and a higher rate of prolonged mechanical ventilation(34.5% vs.15.1%,P=0.001)than the non-obese group.However,there were no difference in the hospital mortality(27.4% vs.38.1%,P = 0.108),ICU mortality(25.0% vs.34.9%,P=0.128)and 60-day mortality(31.0% vs.40.5%,P=0.085).Combined with non-obese group,there were no difference in the obese group in the way of the rate of reintubation,the rate of tracheostomy,the rate of ventilator associated pneumonia,the rate of central line-associated blood stream infection,the rate of deep venous thrombosis and the rate of decubitus,either.In addition,BMI was not a independent risk factor for hospital mortality by the multivariate Logistic regression analysis[RR1.042;95% CI(0.973~1.116);P=0.237].Conclusions In mechanically ventilated ICU patients,obesity is not associated with the mortality,but with longer duration of mechanical ventilation and ICU and hospital stay. |
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